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ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
STUDY ON THE MAXIMUM PRESSURES OF A SOLAR-ASSISTED R744 DIRECT EXPANSION HEAT PUMP FOR WATER HEATING.
Submission Author:
Jéssica Silva , MG
Co-Authors:
Jéssica Silva, Luiz Machado, Willian Moreira Duarte
Presenter: Jéssica Silva
doi://10.26678/ABCM.ENCIT2022.CIT22-0170
Abstract
The use of heat pumps to heat water instead of electric heaters is a way to reduce energy consumption and consequently greenhouse gas emissions. In this context, carbon dioxide (CO2 or R744) as a refrigerant fluid has drawn the attention of several researchers in the refrigeration field. Several works in the literature evaluated the performance of the heat pump, economic performance, energy performance, exergy performance, influence of the geometry in the solar evaporator, but no work presents the behavior of the pressure in the evaporator. In this context, this paper presents a mathematical model for the heat pump evaporator (DX-SAHP) that evaluates the behavior of the pressure in the evaporator when it is not operating but exposed to the sun and the impacts of these pressures on the structural integrity of the components, considering an amount of CO2 mass trapped inside the evaporator varying between 8% and 12%. The meteorological data for solving the mathematical model were taken from INMET website for the day with highest solar radiation in 2022. The maximum R744 pressure for 12% mass inside the evaporator was around 10MPa whereas the maximum work pressure recommended by tube manufacture is 13.2MPa.
Keywords
Numeric model, DX-SAHP, pressure in the evaporator, Solar assisted heat pump, R744 (CO2)
